This invention relates to underwater pile-framed structures such as breakwaters, sea berths, ocean culture facilities and other ocean pile-framed structures and more particularly, to offshore pile-framed structures which are adapted to bear the whole weight of block stacks by means of pile groups.
There have been proposed and practically employed a variety of underwater pile-framed structures for supporting block stacks. In one of the prior arts (1) a flange is secured to a selected point along the length of an upright pile (as shown in Japanese Patent Application Publication No. 6203/1986, for example), in another prior art (2) inner and outer annular wedge members tapering in the opposite directions are disposed about an upright pile to hold the pile in position (as shown in Japanese Laid-Open Patent Application Publication No. 39220/1981, for example) and in a further prior art (3) annular blocks are suspended from the tops of upright piles by means of wire ropes (as shown in Japanese Patent Application Publication No. 17484/1981, for example). In the above-mentioned prior arts, mortar is filled in the annular clearance defined betwen the pile and the hole in the block stack supported by the flanges, fixed support point means or annular members.
The arrangement comprising the piles having the flanges secured thereto (1) has the drawbacks that the flanges interfere with the driving of the piles into the bottom of the seabed and that the flanges on the piles tend to lie in different planes depending upon the degree of precision with which the piles are driven and the geology and unevenness of the seabed. The arrangement in which the inner and outer wedges form the fixed support point means (2) has the drawback that the breakwater structure to be constructed requires a relatively large number of parts and is complicated in construction resulting in difficulty of assembling.
Although the arrangement in which the annular members are suspended from the tops of the piles by means of wire ropes (3) eliminates the drawbacks inherent in the prior arts (1) and (2), in the arrangement (3), the weight of the block stacks is supported only by the tops of the piles through the annular members and wire ropes and the block stacks and piles are practically separate from each other from the view point of construction. That is, although the clearances defined between the pile receiving holes in the block stacks and the piles are filled with mortar and the mortar merely fills up the clearances, it can not be said that the block stacks and piles are integral with each other from the view point of structure. Thus, when either one of the block stacks on one hand and the piles on the other hand are applied external forces thereto, the filling mortar is simply insulated from the block stacks or piles and thus, external forces such as wave force and force of ships in mooring applied to the block stacks can not be smoothly transmitted to the piles or external force such as earthquake applied to the piles can not be smoothly transmitted to the block stacks. Thus, the breakwater structure constructed by the method of the prior art (3) has a quite low resisting force against external force.